I had no idea this existed until it came across AnSaxNet today: The Online Old English Paradigms Project. I ran through it a couple of times, and it appears to work fine. If you're having trouble learning all those paradigms, this ought to help!
I do have one complaint -- it's extremely grumpy regarding diacritical marks. For example, I typed in Ic for the first person singular nominative, and it came back incorrect, with ïc coming back as the "correct" answer. First off, I've always been skeptical of the utility of using diacritical marks for OE, since they're entirely editorial intervention (they don't occur in the manuscripts), and unlike punctuation, don't replicate a commonly-used element of Modern English. Second, an umlaut? Yuck!
Still, when you've got yourself a quiz coming up, this could be a great tool ... if you ignore the insistence on umlauts.